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ECE 207 Purpose The law-pass filter designed in this lab will be used to create a Bode plot of the filter’s gain and make a comparison with the outcome predicted by Matias. Deliverables * — Design calculations for the low-pass filter * — Bode magnitude plot including straight-line predict- ed response and smooth curve of actual response * — Mat.as-generated Bode magnitude plot with smooth curve of actual response superimposed Procedure 1. Design a low-pass filter as shown in Fig. 1. Use a capacitor from your kit (see list on hand-in page) and appropriate resistors to give this filter a pass- band gain of 6 dB and a break frequency of 1.7 kHz, Note that resistance values in op-amp circuits need to be at least 1 kQ and should not be larger than 100 kQ. Show the design calculations on the hand-in sheet. 2. Measure and record the values of the three compo- nents that you chose for your design. Also record the break frequency calculated from these values. 3. With an input voltage V, of about 1 V aus, display both the input and output signals on the scope to be sure they are sinusoidal. 4. Measure the magnitude of the gain of your low-pass filter at enough points to be able to draw a good smooth Bode plot. Use the table on the hand-in sheet. Note that the gain is in dB, which can be measured directly by the pam when properly set. 5. Using the graph paper on the back of the hand-in sheet, draw the predicted straightiine Bode plot for the filter and a smooth curve of the actual re- sponse. The predicted plot is to be based on values calculated from the component values developed in your design. Include proper axis labels and a title. 6. Create a Bode magnitude plot for this filter using Manaz based on the measured component values. Fail 2007 Lab 10—Low-:pass filter A sample of Mattas code is shown below. 7. Draw a smooth curve of the filter’s actual response on the Marias Bode plot. Finishing Complete the table on the hand-in sheet and the Bode dia- gram on the back of that sheet. Attach the Matias plot (with the added actual response) to the hand-in sheet. Turn in these twa pages not later than the beginning of the first class after the lab session. Example of MaTLas code This Matias code will plot the transfer function for a low- pass filter with a passband gain of 16 dB and a break fre- quency of 1 kHz. (Interspersed comments are not part of the Matias code.) The transfer function for this filter is 19 sy 2% 1000 H(s)= Define transfer function as fis) ees=ti('s') Define transfer function for this filter >>t£=10* (16/20) / ((s/ (2*pi*1000) ) +1) Plot Bode from w=100 to 100,000 rad/s >>bodemag (tf, (100, 100000)) Show a grid for easier reading and title the graph >>grid on >ptitle (‘Bode plot of LP filter’) \t Ww Ce Te scope Channel 2 - i Fig. I—Low-page filter 
